The present invention relates to a method of and apparatus for controlling the fuel feeding rate of an internal combustion engine during and after acceleration.
In an internal combustion engine having an electronically controlled fuel injection system which controls the fuel feeding rate by using fuel injection valves or other fuel control valves, the fuel feeding rate is instantly increased by a predetermined increment when the engine is accelerating. Then, the incremental amount of fuel injected as a result of the acceleration operation (hereinafter called as "the acceleration increment") gradually decreases to zero with the lapse of time unless the next acceleration operation occurs. According to the conventional method of controlling the fuel feeding rate, however, the reduction rate of the acceleration increment has been always maintained at a constant value. Therefore, if the required acceleration increment is varied depending upon the operating condition of the engine or upon the acceleration degree of the engine, it is difficult to always obtain optimum reduction characteristics of the acceleration increment. Accordingly, response characteristics of the engine deteriorate during acceleration to impair the acceleration feeling. Furthermore, since the air-fuel ratio becomes too rich, excessive fuel consumption takes place, the efficiency of purifying noxious components in the exhaust gas is reduced and excessive carbon is deposited on the spark plugs.